ABSTRACT

The Troll Olje platform is the first catenary-moored concrete floater ever built. Detail engineering commenced in November 1992, and the substructure should be ready mechanical complete by December 1994. The main challenge has been to develop, design and fabricate a new concept within a tight schedule. This paper describes the main features of the concrete floater and gives an overview of some of the experience gained during the development of the concept.

INTRODUCTION

The Troll Olje platform is a self-contained production and quarter (PQ) platform, which consist of a concrete floater supporting a fully-equipped module support frame (MSF). The modules are living quarter (LQ), utility (M10) and the process (M20) unit. The modules will be lift-installed inshore with maximum onshore/atshore work offering a complete platform ready for production prior to tow-out to the field location. Four subsea clusters with a capacity of 26 production wells are connected to the floater by flexible risers. Pull-in tubes are provided to protect each of the flexible risers and guide them from lower part of the pontoon to the MSF. A ship-impact frame will protect the risers from possible damage due to ship impact. The hull is built entirely of concrete, except for a steel deck which encloses the top of the columns. Mechanical equipment such as pumps etc. will be placed on an steel equipment deck inside the columns. The MSF is supported on the substructure by a single moment-free support on each column, which provides minimum structural interaction between the hull and the MSF. A 16-line passive mooring system will ensure that the FPU is kept in position at the offshore location. The complete substructure will be constructed in a 17m deep dry dock at Han0ytangen, on the west coast of Norway near the city of Bergen.

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